Identification features such as bar codes, optical characters, Radio Frequency Identification (RFID), magnetic or optical strips, and other means of identifying or authenticating objects have been used for purposes of identification, authentication, and tracking and tracing. Recently, “inherent disorder”-based features of objects have also been used either alone or in combination with other identification features to uniquely identify objects and to provide evidence of the authenticity of objects for anti-counterfeiting purposes. An “inherent disorder”-based feature is a feature based on a disordered material, wherein the structure of the disorder is used to identify the object. The disordered material may be a part of the object itself, or may be part of a tag that is affixed to the object. Further, the disordered material may include a disordered coating, composite, or structure.
There are numerous previously known examples of the use of inherent disorder for identification and authentication purposes. For example, Ingenia Technology Limited, of London, UK, has described a system that uses the inherent disorder of fibers within paper, mapped using laser-speckle interferometry, to uniquely identify the paper. A more complete description of this technology can be found in PCT application WO 2006/016114.
Another previously known use of inherent disorder is shown in U.S. Pat. No. 7,380,128, assigned to Novatec, SA, of Montauben, France. This patent shows use of random bubbles within a transparent polymer for identification and authentication. Optical methods are used to read the three-dimensional layout of the bubbles within the polymer. This information can be used to provide a unique signature for a “bubble tag”, which is difficult or impossible to replicate.
Other inherent disorder-based identification and authentication technologies include use of randomly distributed quantum dots or nanobarcodes, use of ink containing magnetic particles arranged in a disordered pattern, use of random “jitter” in the magnetic stripes of credit cards, and use of random distribution of taggant particles that are invisible to human vision on an article (see PCT application WO 2005/104008).
Additional inherent disorder-based tags that use a combination of magnetic and/or magnetisable and/or conductive and/or semi-conductive and/or optically active particles and/or optically distinguishable particles have been reported by the present applicant, Bilcare Technologies. These technologies are further detailed in commonly-owned PCT applications WO 2005/008294, WO 2006/078220, WO 2007/133164, WO 2007/133163, and WO 2009/105040.
Various signal detection systems based on optical, magnetic, and magneto-optical effects are used to read these inherent disorder features. Once read, information on the inherent disorder features can be processed either in the reading device itself or in a back-end computer system to use the information for identification and/or authentication purposes.